Li Shizhen is considered to have been China's greatest naturalist. He was very interested in the proper classification of the components of nature. His major contribution to medicine was the forty year project of sifting through the vast array of herbal lore and writing down the information that was, in his view, a reliable reflection of reality. His book, the Pen T'sao Kang Mu (Bencao Gang Mu; 1596), has been used as a pharmacopoeia, but it was also treatise on botany, zoology, minerology and metallurgy. The book was reprinted frequently and five of the original edition still exist. A rough translation of the herb entries was published in English by two British doctors (Porter and Smith) who were working in China at the end of the 19th century, though extracts of it had been published in Europe since 1656. British researcher B.E. Reid spent 20 years translating an abridged version which was published in 1932.